There is a conventional battery-driven transmission apparatus that decides whether a data transmission function can be used or not based on remaining power of a battery and issues an alarm when it decides that data cannot be sent.
On the other hand, a music distribution system for battery-driven portable terminals is put to practical use. For example, there are a case where a portable terminal downloads MP3 music data, records it in a flash memory to listen to the music using a headphone and a case where latest melodies signaling an incoming call are downloaded to a cellular phone. Furthermore, a portable device such as a portable video player, portable audio player, notebook PC, PDA (Personal Digital Assistant), etc., is driven by a battery and has the function of reproducing digital data such as video data, audio data from recording media. Such portable devices also check the remaining power of the battery and issue an alarm to users when the battery level is low.
However, such conventional battery-driven portable devices only display the remaining power of the battery and there are cases where distribution of data may be incomplete due to a shortage of the remaining power of the battery.
Furthermore, the above-described conventional power saving technology performs power saving processing but does not perform any special reproduction considering the remaining power of the battery and just turns off power when the battery is exhausted, and cannot decide before reproducing desired digital data whether the digital data can be reproduced to the end or not. Further, it cannot efficiently overview data when the battery level is low, either.